Novel anionic polymers of certain insoluble crosslinked polymers of a pka value of at least 16 and alkali and alkaline earth metals



United States Patent 3,316,223 NOVEL ANKONHC POLYMERS OF CERTAIN IN-SOLUBLE CROSSLINKED POLYMERS OF A pKa VALUE OF AT LEAST 16 AND ALKALIAND ALKALINE EARTH METALS Massimo Baer, Longmeadow, and Michael J.Vignale, Lunenburg, Mass., assiguors to Monsanto Company, a corporationof Delaware No Drawing. Original application Oct. 20, 1959, Ser. No.847,472, now Patent No. 3,079,428, dated Feb. 26, 1963. Divided and thisapplication Aug. 8, 1962, Ser. No. 215,519

8 Claims. (Cl. 26080.5)

This application is a division of our copending application, S.N.847,472, filed October 20, 1959, now US. Patent 3,079,428.

This invention relates to insoluble polymeric anionic materials. Moreparticularly, the invention relates to insoluble polymeric anionicmaterials which are useful as purifying agents for removing acidicimpurities from organic liquids.

Because of the sensitivity of anionic polymerization systems to acidicimpurities, i.e., proton donors, which destroy or consume the growingchains and initiator, solvents and monomers to be employed in suchpolymerization systems should be substantially free of impurities havinga pKa value lower than that of the monomers to be polymerized, i.e.,impurities which are more highly acid than the monomers. Many materialsknown to be capable of reacting with the acidic impurities cannot beused to purify the solvents and monomers, because in order to besuitable as a purifying agent in this application a material mustsatisfy these general requirements:

( 1) It must be capable of removing the acidic impurities withoutcontaminating the solvents and/ or monomers with another impurity whichreacts with. anionic initiators, and

(2) It must be inert to the liquid being it must be incapable ofinitiating monomer being purified.

As used throughout the purified, e.g., polymerization of thespecification, terms referring to acidity should be understood asfollows in the sense of the definitions derived from the proton-transfertheory of acids and bases:

(1) Acid-product obtained by adding a proton to. a base, a base beingany substance which, because of an unshared electron pair, can accept aproton,

(2) Conjugate acidacid related to particular base in being the productobtained by adding a proton to that base,

(3) pKa value-negative logarithm of the dissociation constant of anacid.

It will be noted that, when understood in this sense, the term acid isnot restricted to the inorganic, carboxylic, and sulfonic compoundsconventionally designated as acids, i.e., compounds having low pKavalues of up to about 10, but also embraces compounds of much higher pKavalue.

One object of this invention is to provide means for purifying organicliquids of acidic impurities, i.e., impurities having a pKa value lowerthan that of the organic liquid.

Another object is to provide means for purifying organic liquids ofacidic impurities without contaminating the liquids with otherimpurities capable of reacting with anionic polymerization initiators.

A further object is to provide means for purifying organic liquids ofacidic impurities without causing reaction of the liquid being purified.

These and other objects are attained by purifying an 3,316,223 PatentedApr. 25, 1967 organic liquid of acidic impurities by contacting theliquid with an insoluble polymeric anionic material which is inert tothe liquid, said anionic material being an alkali metal salt or alkalineearth metal salt of an insoluble, cross-linked polymer containing aplurality of units capable of reacting with an alkali metal or alkalineearth metal to form an anion, the conjugate acid of said salt having apKa value of at least 16.

The following examples are given to illustrate the invention. Partsmentioned are parts by weight.

Example I.-Preparati0n 0f purifying agent A suitable reaction vessel ischarged with 300 parts of water, followed by addition of 1 part ofbentonite with agitation. The slurry is heated to 65-70" C., and amixture of 50 parts of vinyl fiuorene, 40 parts of styrene, 10 parts ofdivinyl benzene, and 1 part of benzoyl peroxide is added thereto. Theair in the vessel is purged With nitrogen, and the pressurized vesselcontents are heated at 88-90 C. for 20 hours and then at 115-120 C. for12 hours. The batch is cooled and discharged into a centrifuge where thesuspension is collected and Washed with hot water. The polymer beads aredried in a forced draft air oven for 12 hours at 110-120" C. and washedwith 1,2-dimethoxyethane to form substantially pure beads ofcross-linked vinyl fluorene-styrene-divinyl benzene (50:40:10)terpolymer.

A molar solution of sodium naphthalene in 1,2-dimethoxyethane is passedthrough a column containing the polymer beads in order to replace theactive hydrogen atoms of the vinyl fluorene units with sodium. The efiluent from the column, a solution of dihy-dronaphthalene and sodiumnaphthalene in 1,2dimethoxyethane, is collected in a receiver. Thetreatment of the polymer with sodium naphthalene solution is continueduntil the concentration of sodium naphthalene in the eilluent solutionindicates no further capacity of the polymer to react with sodium. Thecolumn of beads is then washed with 1,2-dimethoxyethane to removeresidual sodium naphthalene and dihydronaphthalene, The product of thetreatment is an insoluble polymeric anionic material in whichsubstantially all of the vinyl fluorene units of the cross-linked vinylfluorene-styrene-divinyl benzene (50:40:10) terpolymer have beenconverted to the sodium salt.

The same procedure of interpolymerizing monomers by suspensionpolymerization to form beads of a crosslinked polymer and then reactingthe beads with an alkali metal naphthalene to form an insolublepolymeric anionic material is used to prepare the following salts:

(1) Sodium salt of a styrene-N,N-diallylacrylamide (:20) copolymer inwhich substantially all of the active hydrogen atoms of theN,N-diallylacrylamide units have been replaced with sodium.

(2) Lithium salt of a vinyl benzyl alcohol-divinyl benzene (90:10)copolymer in which substantially all of the active hydrogen atoms of thevinyl benzyl alcohol units have been replaced with lithium,

(3) Lithium salt of a styrene-vinyl indene-divinyl benzene (60:30:10)terpolymer in which substantially all of the active hydrogen atoms ofthe vinyl indene units have been replaced with lithium,

(4) Potassium salt of a styrene-vinyl fluorene-divinyl benzene(60:30:10) terpolymer in which substantially all of the active hydrogenatoms of the vinyl fluorene units have been replaced with potassium, and

(5) Potassium salt of a p-aminostyrene-styrene-divinyl benzene(80:10:10) terpolymer in which substantially all of the active hydrogenatoms of the p-aminostyrene units have been replaced with potassium. Y

Example II .-Purificatin of organic liquids Six organic liquids arepurified, using the indicated insoluble polymeric anionic materials ofExample I as purifying agents:

Organic Liquid Purifying Agent Benzene Na salt of vinylfiuoreue-styrencdivinyl benzene (50:40:10) terpolymer. Na salt ofstyrenc-N,N-di-allylacrylamide (80:20) copolymer. Methyl methacrylate.Li salt of vinyl benzyl alcohol-divinyl benzene (90:10) copolymer.

LZ-dimethoxyethane.

Styrene Li salt of styrene-vinyl indenedivinyl benzene (60:30:10)terpolymer. Butadicnc K salt of styrene-vinyl fluorcnc-divinyl benzene(60:30:10) terpolyrner. Isoprene K salt ofp-aminostyrene-styrene-divinyl bcnzene (80:10:10) terpolyrner.

A suitable reaction vessel is charged with half of a carefully-degassedsolution of 100 parts of styrene in 980 parts of 1,2-dimethoxyethane,followed by the addition with agitation of half of a substantially pure,carefullydegassed solution of about 0.13 part of sodium naphthalene in 20 parts of 1,2-dimethoxyethane, an inert atmosphere being maintained inthe vessel throughout the reaction. The reaction results in a smallyield of polystyrene.

The second half of the carefully-degassed monomer solution described inthe previous paragraph is passed through a column of beads of the sodiumsalt of the vinyl fluorene-styrene-divinyl benzene (50:40:10) terpolymerof Example I. The effluent from the column is charged to a suitablereaction vessel, followed by the addition with agitation of the secondhalf of the substantially pure, carefully-degassed initiator solution,an inert atmosphere being maintained in the vessel throughout thereaction. The reaction results in substantially quantitative conversionof styrene to high molecular weight polystyrene.

The present invention relates to novel insoluble polymeric anionicmaterials and to their use as purifying agents for organic liquidscontaining acidic impurities.

The insoluble polymeric anionic materials are the akali metal salts andalkaline earth metal salts of insoluble, cross-linked polymerscontaining a plurality of units capable of reacting with an alkali metalor alkaline earth metal to form an anion, the conjugate acids of saidsalts having pKa values of at least 16.

Exemplary of known with alkali metals or alkaline earth metals to formthe purifying agents of the invention are copolymers of vinyl toluene,vinyl isopropyl benzene, vinyl benzyl alcohol, p-acetylstyrene,p-aminostyrene, vinyl pyridine, ethylenimine, or other polymerizablecompound which, as a chemically-combined unit of a polymer, contains anactive hydrogen replaceable with alkali metal or alkaline earth metal,or mixtures of such compounds, with one or more cross-linking agentssuch as divinyl benzene, divinyl toluene, divinyl xylene, divinylethylbenzene, diisopropenyl benzene, trivinyl benzene, divinylnaphthalene, trivinyl naphthalene, polyvinyl anthracene, etc., andoptionally with one or more other interpolymerizable monomers, e.g.,vinyl ethers, styrene, etc.

Other known polymers utilizable in preparing the purifying agents of theinvention are copolymers in which the cross-linking agent, as achemically-combined unit of a polymer, contains active hydrogenreplaceable with alkali metal or alkaline earth metal. Suchcross-linking agents are, for example, p-diallyl benzene, diallylmelamine, N,

polymers which can be reacted 0 N-diallyl-acrylamide, allyl silanes, andthe like, which in the course of polymerization leave residual unreactedallyl groups. These cross-linking agents are copolymerized with one ormore monoethylenically-unsaturated copolymerizable monomers which may,if desired, also be monomers which, as a chemically-combined unit of apolymer, contain aot-ive hydrogen replaceable with alkali metal oralkaline earth metal. Alternatively, the crosslinking agent mayconstitute the only polymeric component capable of reacting with analkali metal or alkaline earth metal to form an anion.

However, since the only requirement of the polymers with which alkalimetal or alkaline earth metal is reacted to form the purifying agents ofthe invention is that they be insoluble, cross-linked polymerscontaining a plurality of units capable of reacting with alkali metal oralkaline earth metal to form an anion and that they have a pKa value atleast as high as 16, and since monomers capable of contributing suchunits containing active hydrogen are already well known, various otherpolymers utilizable in preparing the purifying agents will be obvious tothose skilled in the art. The polymers us-ually should contain about140%, preferably 545%, by weight of units of the cross-linking agent andat least about 10% by weight of units capable of reacting with alkalimetal or alkaline earth metal to form an anion. They can be prepared byany suitable polymerization technique, advantageously by suspensionpolymerization of the monomers to form polymer beads, as demonstrated inExample I, or by impregnating an inert carrier, e.g., silica gel,alumina, calcium sulfate, carbon black, diatomaceous earths, clays,etc., with the monomers and then polymerizing to form a thin coating ofpolymer on a large surface of the inert carrier.

The purifying agents of the invention are prepared by reacting theseinsoluble, cross-linked polymers with a metal or Group IA or IIA of theperiodic classification of the elements, i.e., with Li, Na, K, Rb, Cs,Mg, Ca, Ba, or Sr, to replace the active hydrogen atoms of the polymerwith metal, thus forming an insoluble polymeric anionic material. Thisreaction can be accomplished by contacting the polymer in any suitablemanner with a solution or dispersion of the metal in an inert liquidmedium orfmore efficiently, by contacting the polymer with a solution ordispersion in an inert liquid medium of an organo-metallic compound ofthe metal whose conjugate acid is weaker than that contained in theinsoluble polymer. Advantageously, the polymer is reacted with the metalby contacting it with a solution of an ion-radical adduct, e.g., sodiumnaphthalene, in a polar solvent such as 1,2-dimethoxyethane, asdemonstrated in Example I.

The treatment of the polymer with the metal-containing composition ispreferably continued until the capability of the polymer to react withthe alkali metal or alkaline earth metal is exhausted in order tofurnish the polymer with the maximum number of possible sites forsubsequent reaction with acidic impurities contaminating the organicliquids to be purified. However, this exhaustion of the capability ofthe polymer to react with alkali metal or alkaline earth metal isobviously not required to make the polymeric anionic materials effectiveas purifying agents, particularly when the polymer contains a largenumber of units capable of reacting with alkali metal or alkaline earthmetal. After completion of the treatment of the insoluble polymer withthe alkali metal or alkaline earth metal, the polymeric anionic materialis preferably washed with an inert solvent, e.g., liquid ammonia, toremove unreacted metal, metal compound, or residue of metal compound.

The insoluble polymeric anionic materials of the invention are effectiveas agents for purifying organic liquids of acidic impurities. Theinvention is particularly applicable to the purification of organicliquids to be employed in anionic polymerization systems, e.g.,anionically-polymerizable vinylidene monomers such as styrene,

vinyl toluene, 0-, m-, and p-methoxystyrenes, butadiene, isoprene,methyl methacrylate, etc., or solvents such as benzene, hexane,tetrahydrofuran, 1,2-dimethoxyethane, etc., but it can also be appliedto the purification of any organic liquid which is contaminated byimpurities having a pKa value lower than that of the liquid.

Purification of the organic liquids is accomplished by contacting theliquid with the purifying agent in any suitable manner, advantageouslyby passing the liquid through a column of beads of the purifying agent,as demonstrated in Examples II and III. After being used to purify anorganic liquid, the insoluble polymeric anionic material can beregenerated by repeating the metal treatment used in preparing thepurifying agent.

Since the various organic liquids which can be purified of acidicimpurities by the insoluble polymeric anionic materials of the inventionhave varying degrees of reactivity with anionic materials, care must betaken in the choice of a purifying agent for a particular organic liquidto insure removal of the acidic impurities without caus ing undesirablereaction of the lequid. The suitability of a particular insolublepolymeric anionic material as a purifying agent for organic liquids canreadily be determined by routine experimentation, and in many cases thisdetermination of the suitability of the anionic material is facilitatedby the fact that the reactivity or lack of reactivity of many of theorganic liquids with anionic materials of varying pKa values is alreadyknown. For greatest efiiciency in removing acidic impurities, thepurifying agent should have as high a pKa value as is consistent withthe requirement that it be inert to the organic liquid being purified.

The invention is particularly advantageous in that it provides novelinsoluble polymeric anionic materials which, when used as purifyingagents for organic liquids, enable the removal from solvents andmonomers of substantially all of the acidic impurities which interferewith anionic polymerization without contaminating the solvents andmonomers with other impurities which would react with anionicinitiators.

It is obvious that many variations may be made in the products andprocesses set forth above without departing from the spirit and scope ofthis invention.

What is claimed is:

1. An adduct of (a) a metal of the group consisting of alkali metaalsand alkaline earth metals and (b) an insoluble, cross-linked polymercontaining a plurality of units of a monomer of the group consisting ofvinyl indene, vinyl fluorene, vinyl toluene, vinyl isopropyl benzene,vinyl benzyl alcohol, p-acetylstyrene, vinyl pyridine, ethylenimine,p-diallyl benzene, dially melamine, and N,N-diallylacrylamide, saidpolymer having a pKa value of at least 16 and at least about 10% byweight of units capable of reacting with alkali metal or alkaline earthmetal to form an anion.

2. The adduct of claim 1 wherein the metal is lithium.

3. The adduct of claim 1 wherein the metal is sodium.

4. The adduct of claim 1 wherein the metal is potassium.

5. The adduct of claim 1 wherein the insoluble, crosslinked polymer is avinyl fluorene-styrene-divinyl benzene terpolymer.

6. The adduct of claim 1 wherein the insoluble, crosslinked polymer is astyrene-N,N-diallylacrylamide copolymer.

7. The adduct of claim 1 wherein the insoluble, crosslinked polymer is avinyl benzyl alcohol-divinyl benzene copolymer.

8. The adduct of claim 1 wherein the insoluble, crosslinked polymer is astyrene-vinyl indene-divinyl benzene terpolymer.

References Cited by the Examiner UNITED STATES PATENTS 2,366,008 12/1944DAlelio 260-2.l 2,534,193 12/1950 Emerson 2609l.3 2,592,349 4/1952Skogseid 2602.1 2,663,702 12/19'53 Kropa 260-2.1 2,903,440 9/1959Heiligmann 26088.1 3,055,860 9/1962 Baer et al 26088.2

FOREIGN PATENTS 616,134 1/ 1949 Great Britain.

I. C. MARTIN, C. A. WENDEL, Assistant Examiners.

1. AN ADDUCT OF (A) A METAL OF THE GROUP CONSISTING OF ALKALI METALS ANDALKALINE EARTH METALS AND (B) AN INSOLUBLE, CROSS-LINKED POLYMERCONTAINING A PLURLITY OF UNITS OF AMONOMER OF THE GROUP CONSISTING OFVINYL INDENE, VINYL FLUORENE, VINYL TOLUENE, VINYL ISOPROPYL BENZENE,VINYL BENZYL ALCOHOL, P-ACETYLSTYRENE, VINYL PYRIDINE, ETHYLENIMINE,P-DIALLYL BENZENE, DIALLY MELAMINE, AND N,N-DIALLYLACRYLAMIDE, SAIDPOLYMER HAVING A PKA VALUE OF AT LEAST 16 AND AT LEAST ABOUT 10% BYWEIGHT OF UNITS CAPABLE OF REACTING WITH ALKALI METAL OR ALKALINE EARTHMETAL TO FORM AN ANION.
 5. THE ADDUCT OF CLAIM 1 WHEREIN THE INSOLUBLE,CROSSLINKED POLYMER IS A VINYL FLUORENE-STYRENE-DIVINYL BENZENETERPOLYMER.
 8. THE ADDUCT OF CLAIM 1 WHEREIN THE INSOLUBLE, CROSSLINKEDPOLYMER IS A STYRENE-VINYL INDENE-DININYL BENZENE TERPOLYMER.